#1  
Old 04-27-2012, 04:25 PM
Serf
 
Join Date: Aug 2011
Location: Mesa, Arizona
Posts: 20
Default Arch Question

OK, I've seen many, many arches in this forum. Would the one pictured below be just as strong - or stronger? Using a 9" x 4.5" firebrick, wouldn't it be like just leaving out the mortar with more smaller firebricks? Thanks for any insight

Russ
Attached Thumbnails
Arch Question-arch-example.jpg  
Reply With Quote
  #2  
Old 04-27-2012, 04:36 PM
Tscarborough's Avatar
Il Pizzaiolo
 
Join Date: Oct 2009
Location: Ausitn
Posts: 2,994
Default Re: Arch Question

It is very shallow and would require large buttresses.
Reply With Quote
  #3  
Old 04-27-2012, 09:13 PM
david s's Avatar
Il Pizzaiolo
 
Join Date: Mar 2007
Location: Townsville, Nth Queensland,Australia
Posts: 4,699
Default Re: Arch Question

Quote:
Originally Posted by Tscarborough View Post
It is very shallow and would require large buttresses.
That's right. The shallower the arch (the larger the radius) then the greater is the sideways thrust. That is why the semi circular Roman arch is so strong and does not need much buttressing.
Reply With Quote
  #4  
Old 04-28-2012, 09:33 AM
Serf
 
Join Date: Aug 2011
Location: Mesa, Arizona
Posts: 20
Default Re: Arch Question

Thanks guys. That lets me breath easier because this will be a simple arch to make and should look good (although it will be behind a face brick arch). I was planning on placing very large buttresses, with thermal breaks made out of insulating firebrick, on either side of the vent area to contain the outward forces. I'm trying to make the arch high (10") enough to be usable for both bread and pizza baking but to stay with the golden 63%.

Russ
Reply With Quote
  #5  
Old 04-28-2012, 10:03 AM
GianniFocaccia's Avatar
Il Pizzaiolo
 
Join Date: Jun 2009
Location: Disneyland, CA
Posts: 1,365
Default Re: Arch Question

Russ,

From your drawing, it appears your design has standard firebricks with their narrow side facing down. Two questions: If so, do you plan to support a vent/flue with this arch? Is your design made to simplify construction of the arch?
Reply With Quote
  #6  
Old 04-28-2012, 12:39 PM
Serf
 
Join Date: Aug 2011
Location: Mesa, Arizona
Posts: 20
Default Re: Arch Question

GianniFocaccia-
Yes, that was the plan. The vent area will be defined by two arches, front and back, with the rear one accepting the down-sloping firebricks from the cooking arch (its a semicircular arched cooking area like perk1018's but with external chimney). The chimney is an 8" x 12" flue pipe, 24" long with a spark suppressor/rain roof. Do you think that it would be too weak? I want to have arches spanning 19" at the rear and 24" at the front, behind a decorative arch.
Reply With Quote
  #7  
Old 04-28-2012, 12:42 PM
Serf
 
Join Date: Aug 2011
Location: Mesa, Arizona
Posts: 20
Default Re: Arch Question

GianniFocaccia
I should have read everything you said before replying...
The design of the arch was to have a very small rise using standard firebricks to allow for a more uniform opening height without resorting to steel. Wouldn't using solid firebrick be better than several smaller wedges that have to be mortared together?
Russ
Reply With Quote
  #8  
Old 04-28-2012, 02:08 PM
GianniFocaccia's Avatar
Il Pizzaiolo
 
Join Date: Jun 2009
Location: Disneyland, CA
Posts: 1,365
Default Re: Arch Question

Quote:
Wouldn't using solid firebrick be better than several smaller wedges that have to be mortared together?
From my limited understanding of vaulted structures, I believe an arch with a more conventional line of thrust is stronger than your design. I'm also not used to seeing an arch (or set of arches) that is only 2 1/2" thick. The strength provided by a mortared joint is more than adequate and there appears to be little gained by designing an arch with only two joints versus 10 or 11 (or more). An oven expands and contracts through its thermal cycles, and as I understand it, mortar plays an important part in absorbing and deflecting some of the heat so that all the stresses aren't placed directly on bricks, which can make them crack. Even in a shallower arch like yours, I think multiple bricks makes for a stronger arch.

John
Reply With Quote
  #9  
Old 04-28-2012, 05:53 PM
Tscarborough's Avatar
Il Pizzaiolo
 
Join Date: Oct 2009
Location: Ausitn
Posts: 2,994
Default Re: Arch Question

As a rule, the more segments (bricks) the better, not because it is an arch but because it is subjected to extreme heat cycling. Consider it engineered crack design.
Reply With Quote
  #10  
Old 04-29-2012, 09:48 AM
Serf
 
Join Date: Aug 2011
Location: Mesa, Arizona
Posts: 20
Default Re: Arch Question

Well, if figures there was a reason that my simpler arch idea was not being used. So, I will go with a traditional, but shallow, multi-segmented arch. Many thanks for the feedback. You probably saved me from some serious future problems.
Russ
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Need advice on chimney and outer arch construction Jayson Design Styles, Chimneys and Finish 28 04-21-2013 05:20 PM
Arch Mortar Joint Question rodeair Tools, Tips and Techniques 12 06-07-2011 09:37 PM
firebrick arch vent question mrgweeto Getting Started 16 04-16-2009 09:11 AM
Forno Bravo landing and arch paint question anemosss Design Styles, Chimneys and Finish 2 01-29-2008 09:53 PM
brick thickness for top of landing arch waynebergman Pompeii Oven Construction 2 11-28-2007 09:29 AM


All times are GMT -7. The time now is 04:09 PM.

Powered by vBulletin® Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Search Engine Friendly URLs by vBSEO 3.6.0
2006/10 Forno Bravo, LLC